Apparatus for drawing glass fibers



Feb. 26, 1952 R. R. BAsTlAN ErAl. 2,586,774

APPARATUS FOR DRAWING GLASS FIBERS Filed Aug. 6,' 1948 saar/olv Paf/1 of fiber drawn by grav/'ff Patented F eb. 26, 1952 'APPARATUS FOR DRAWING GLASS FIBERS Richard R. Bastian, Toledo, and Glenn Berkeble,

Waterville, Ohio, assignors to Lucas Development, Inc., Toledo, Ohio, a corporation of Ohio Application August 6, 1948, Serial No. 42,804

3 Claims. l

This invention Yrelates to a machine for forming glass iibers and is particularly directed to an apparatus lusable for the production of long continuous fibers agglomerated into a product-commercially known as bonded mat, Valthough it is applicable to other uses.

It has heretofore been proposed to form the long, relatively rcoarse fibers for a matted product by the usual blowing process in which the fiber issuing from an orifice in the melting tank is entrained in a rapidly moving air stream and thus attenuated. This process vproduces a satisfactory product but is expensive to operate because of the investment involved in and the maintenance o-f the high pressure Acompressors required. It has also been proposed to utilize'low pressure air in large volumes to blow fibers as they issue from the melting pot orifices against a chain or other belt having relatively large perforations in such a manner that each plastic ber deforms `and patrially enters the perforations and is thus elongated by motion of :the belt or chain. This operation `produces a crimped fiber that is not entirely satisfactory for many uses. If the air pressure or forming temperature is reduced to the point Where no mechanical engagement between .the berand belt ,perforations takes place so that va straight ber should result, the-tractiveforce is solow that no drawing, or haphazard drawing only, `of the fibers Itakes place.

It is the primary object of the invention to provide an apparatus for the mechanical drawing of glass fibers by which the fibers produced are straight -and continuous and which requires `only low pressure air.

Another object of the `invention is to provide an apparatus which 'reduces the degree of skill required for its operation `and maintenance, so that the resulting product may be sold economically and thus widely used.

Still-another object of the invention is to provide an apparatus for the production of long, straight, continuous bers-and which may be utilized to produce iibers of widely varying diameters at the selection of the `operator merely by the adjustmentof operating speeds and temperatures, and in which such adjustments, once made, are reliably maintained.

Other objects and advantages of the invention will become apparent from fthe following specification, reference being had to the accompanying drawing which discloses, somewhat diagrammatically, in a perspective View with parts insection. a glass ber drawing machine embodying the present invention.

Referring to the drawing, .the machine is shown in connection with a tank Il in which molten glass is maintained atan adjustable temperature by .means of any 4conventional'heating system .either electric or combustion. Itis `preferred to use a combustion .furnace in .which a greater than desired in the final product if gravity alone were relied on to maintain now. It is known in the art that fibers may be attenuated with nearly perfect uniformity vby exertinga constant tractive force thereon, or otherwise establish'ing a constant acceleration during the period in which the glass remains plastic.

Below and laterally offset from the orifices I4, the present invention provides a porous -belt or attenuator 2D driven by conventional rollers I6,

I8. In known devices the direction of movement of such pulling devices has been substantially vertical, as above noted. In the present instance, how-ever. the line of movement is displaced from the vertical and in the preferred form is nearly horizontal. The interior of the perforate belt or attenuator 20 is divided into lzones of different pressure, the first zone 2l beingunder negative pressure with respect to the pressure which the fibers first encounter and the second zone 22 being at a higher, positive pressure.

The attenuating belt 20 may have its undersur'face exposed for some distance after the bers are first picked up although its upper surface is enclosed in suitable housing or covered by a plate 23 to prevent the entrance of air through the upper surface of the belt into chamber 2l. At the end of chamber 'Il the bers Venter a hood or deliverychamber havinga ywall 24 which terminates below the belt 20. It has been found in practice that the clearance at this point may be as Ymuch as 2 without seriously interfering with the formation of the fibers. The wall 24 coincides with an inner wall 2G within thevbelt by which the zones 2| and 22 are separated.

After passing wall /24 the fibersenter a `deliv ery chamber 30 in which the formed bers areremoved Ifromthe attenuating belt 20 and delivered as a matted irregularly arranged mass on a conveyor v32 if bonded mat is being produced, or

to other suitable collectors if the fibers are beingcourse, be ,such as to take into account the mat thickness.

The conveyor 32 is operated by a variable speed i motor and the speed of operation is selected Ain dependence on the number of orifices that are operating properly. If several of the orifices fiood so that the fiber therefrom is too thick or become plugged with a bead of glass or other material it is not necessary to shut down the equipment but operation may be continued by accumulating properly formed fibers from the remaining orifices and operating conveyor 32 at somewhat reduced speed. With known devices it is necessary to shut down the equipment and clean out orifices that for some reason have developed a tendency to flood and thus produce beads or irregularities in the fiber.

Once the attenuating belt 20 and convevor 32 are in motion, and the pressure differentials established within zones 2| and 22 fibers may be started from the orifice plate l2 in the usual manner. The fibers are drawn down manually to a point below the level of belt 2li and the end bead broken ofi'. The operator then throws the fiber against the undersurface ofl belt 20. By reason of the pressure differential existing in zone 2| with respect to the exterior of the belt the fiber is held against the surface of the belt and since it is still plastic, is attenuated. It has been found that pulling of the fiber almost without slippage is obtained bythe horizontal or angular disposition of the belt relative to the initial direction of fiber movement, as this disposition of the parts appears to set up a winch-like action on the fiber. The fiber thus travels along with the surface of the attenuating` belt 20. The ultimate diameter of the fiber, that is its degree of attenuation, is governed in part by the linear` speed of belt 20 which may be readily adjusted.`

since the glass is still in a plastic state when the belt is first engaged. It will be apparent, however, that belt speed is only one factor determining fiber size and that glass composition, operating temperature and orifice size and shape enter into this determination.

As the glass leaves the orifice I 4 it is in a highly plastic condition and the acceleration imparted to it attenuates the strand. The plasticity remains only for the first few inches and by the time the fibers have reached the belt the glass has become fully set. The fibers are then carried along belt 20 and subseouently dislodged by the positive pressure of air blowing outwardly from zone 22. The fibers are then collected on conveyor 32 and discharged as a mass into a subseouent bonding station. Those fibers that may adhere to the belt after passing the removal area may be brushed off by any suitable means such as a stationary brush 40. v

Should one of the many bers that are drawn simultaneously become broken, the end adjacent the orifice plate will drop by gravity and will not engage the attenuating belt. These ends are usually accompanied by the formation of beads that are undesirable in the finished product and that must be removed. It is for this reason that the surface of belt 20 is laterally removed from thexaxis of the orifices I4. The operator makina periodic inspections of the equipment breaks oli the bead and starts the fiber again by throwing it against the porous belt where it is picked up and attenuated.

While the invention has been described in connection with a specific form and disposition of the parts it should be expressly understood that numerous modifications and changes may be made without departing from the scope of the appended claims.

What we claim is:

1. Apparatus for forming glass fibers flowing downwardly from a supply of molten glass, which comprises a porous endless belt positioned in an approximately horizontal plane and having one end thereof in substantially tangential contact with the downwardly fiowing glass fibers, means to drive said belt at a velocity greater than the initial velocity of the glass fibers and in a direction such that the belt is moving in the same direction as the glass fibers at the point of contact, fluid pressure means for holding the glass fibers against the under side of the belt adiacent the contacting end, and additional fiuid pressure means oppositelv directed through and away from the under side of the belt adiacent the opposte end thereof vto remove the glass fibers therefrom.

2. Apparatus for forming fibers of glass fiowing downwardly from a supply of molten glass, which comprises an approximately horizontal porous endless belt having one end in substantially tangential contact with the downwardly flowing fibers of glass, means for driving the belt at a velocity greater than the initial velocity of the glass fibers and in a direction such that the belt is moving in the same direction as the glass fibers at the point of contact, means dividing the interior of the belt into two compartments, means within the compartment adjacent the contacting end for creating a low pressure to hold the glass fibers against the under side of the belt as they pass thereunder, and means in the other compartment creating a high pressure area therein to remove the glass fibers from the belt as it passes thereunder.

3. Apparatus for forming fibers of glass flowing downwardly from a supply of molten glass. which comprises an approximately horizontal porous endless belt having one end in substantially tangential contact with the downwardly flowing fibers of. glass, means for driving the belt at a velocity greater than the initial velocity of the glass fibers and in a direction such that the belt is moving in the same direction as the glass fibers at the point of contact, means dividing the interior of the belt into two compartments, means within the compartment adjacent the contacting end for creating a low pressure to hold the glass fibers against the under side of the belt as they pass thereunder, and means within the second compartment for blowing the glass fibers free from the endless belt as it passes thereunder, means positioned below the second compartment and adapted to collect the glass fibers blown free from said endless belt, and means for driving said Vlast means at a predetermined speed to form a mat of predetermined thickness.

RICHARD R. BAsTrAN. GLENN BERKEBILE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

